C2 Engine Offset
07-26-2015, 05:15 PM
#1
C2 Engine Offset
As most of you probably know, the engine in the 1963 (and I assume all C2 small-block) Corvettes is offset slightly to the passenger side of the chassis centerline. Question: Are the 396 and 427 engines in subsequent C2 Corvettes also offset?
07-26-2015, 05:19 PM
#2
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They all used the same frame. So yes.
07-26-2015, 05:20 PM
#3
Team Owner
IIRC it was stated on here that the offset was to make sure the U-joints have at least a small angle on them .... they aren't made to operate in a dead straight-on configuration. If that is true (others will confirm I'm sure) then that has nothing to do with engine size and should apply to them all.
07-26-2015, 05:49 PM
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07-26-2015, 05:56 PM
#6
Safety Car
IIRC it was stated on here that the offset was to make sure the U-joints have at least a small angle on them .... they aren't made to operate in a dead straight-on configuration. If that is true (others will confirm I'm sure) then that has nothing to do with engine size and should apply to them all.
That is incorrect. The centerline of the entire drivetrain is offset, The trans output shaft is on the same horizontal centerline as the rear pinion.
They get the angle to assure U joint life from the vertical offset of the centerline.
I have heard many different reasons, including more footroom for the driver. The most likely reason was so that the halfshafts are the same length on the rear end. Different length halfshafts would make for a funky handling car. The pinion in the rear is offset exactly the same amount from the center of the carrier assembly. This allowed them to shift the rear end over that amount and keep the halfshafts exactly the same length. This is not a problem on solid axle cars, they just make one axle shorter and center the pinion. Not a good option on an independent rear car.
This came back to haunt me on my 65 coupe project, as I used a Winters Quickchange center section on the C6 rear suspension. Unfortunately, the Quickchange rear uses a centered pinion, and I failed to move the side of the tunnel over 1", so when I went to put the driveshaft in, it would not clear the side of the tunnel!
Nothing like cutting up the floor a an already painted car.
Regards, John McGraw
07-26-2015, 06:00 PM
#7
Team Owner
Frankie,
That is incorrect. The centerline of the entire drivetrain is offset, The trans output shaft is on the same horizontal centerline as the rear pinion.
They get the angle to assure U joint life from the vertical offset of the centerline.
I have heard many different reasons, including more footroom for the driver. The most likely reason was so that the halfshafts are the same length on the rear end. Different length halfshafts would make for a funky handling car. The pinion in the rear is offset exactly the same amount from the center of the carrier assembly. This allowed them to shift the rear end over that amount and keep the halfshafts exactly the same length. This is not a problem on solid axle cars, they just make one axle shorter and center the pinion. Not a good option on an independent rear car.
This came back to haunt me on my 65 coupe project, as I used a Winters Quickchange center section on the C6 rear suspension. Unfortunately, the Quickchange rear uses a centered pinion, and I failed to move the side of the tunnel over 1", so when I went to put the driveshaft in, it would not clear the side of the tunnel!
Nothing like cutting up the floor a an already painted car.
Regards, John McGraw
That is incorrect. The centerline of the entire drivetrain is offset, The trans output shaft is on the same horizontal centerline as the rear pinion.
They get the angle to assure U joint life from the vertical offset of the centerline.
I have heard many different reasons, including more footroom for the driver. The most likely reason was so that the halfshafts are the same length on the rear end. Different length halfshafts would make for a funky handling car. The pinion in the rear is offset exactly the same amount from the center of the carrier assembly. This allowed them to shift the rear end over that amount and keep the halfshafts exactly the same length. This is not a problem on solid axle cars, they just make one axle shorter and center the pinion. Not a good option on an independent rear car.
This came back to haunt me on my 65 coupe project, as I used a Winters Quickchange center section on the C6 rear suspension. Unfortunately, the Quickchange rear uses a centered pinion, and I failed to move the side of the tunnel over 1", so when I went to put the driveshaft in, it would not clear the side of the tunnel!
Nothing like cutting up the floor a an already painted car.
Regards, John McGraw
07-26-2015, 07:48 PM
#8
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07-26-2015, 08:18 PM
#9
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Quoting Zora's 1963 SAE paper on the design and development of the 1963 Corvette, page 2:
"To achieve a [47/53 front-rear weight] distribution in this range, the passenger compartment was placed as far back as possible and the engine centerline was offset one inch to the right, taking advantage of the fact that passenger foot room requirements are less than those of the driver. This offset also reduced the width of the driveshaft tunnel, because the crankshaft and offset rear axle pinion were now on the same [plan view] centerline."
"To achieve a [47/53 front-rear weight] distribution in this range, the passenger compartment was placed as far back as possible and the engine centerline was offset one inch to the right, taking advantage of the fact that passenger foot room requirements are less than those of the driver. This offset also reduced the width of the driveshaft tunnel, because the crankshaft and offset rear axle pinion were now on the same [plan view] centerline."
07-26-2015, 08:50 PM
#10
Quoting Zora's 1963 SAE paper on the design and development of the 1963 Corvette, page 2:
"To achieve a [47/53 front-rear weight] distribution in this range, the passenger compartment was placed as far back as possible and the engine centerline was offset one inch to the right, taking advantage of the fact that passenger foot room requirements are less than those of the driver. This offset also reduced the width of the driveshaft tunnel, because the crankshaft and offset rear axle pinion were now on the same [plan view] centerline."
"To achieve a [47/53 front-rear weight] distribution in this range, the passenger compartment was placed as far back as possible and the engine centerline was offset one inch to the right, taking advantage of the fact that passenger foot room requirements are less than those of the driver. This offset also reduced the width of the driveshaft tunnel, because the crankshaft and offset rear axle pinion were now on the same [plan view] centerline."
07-26-2015, 08:52 PM
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07-26-2015, 08:59 PM
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07-27-2015, 01:31 AM
#15
Yes. Thank you for your response and confirmation that small- and big-block C2 frames are identical. I had assumed that there was still an unlikely but slight chance that the offset was effected by the mounts rather than the frame horns. About 35 years ago, I replaced the front mounts on the '65 375 I owned at the time (the rubber separated), but I can't recall if they were symmetrical.
07-27-2015, 06:57 AM
#16
Team Owner
So, the offset was to increase driver footwell space mainly and the pinion alignment was a secondary, side benefit ? ....that's the way the quote reads...
07-27-2015, 11:27 AM
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The pinion alignment allowed a narrower drive shaft tunnel. Don't try to make something easy, difficult.
'61-'67 Chevy II's had the engine offset to the right about an inch. It may have been done get get driver's foot room or it may have been done to get real estate for the V-8 engine. Don't know.
Second generation Chevy II/Nova and first generation Camaros had the BB engines offset to the right at both the engine mounts and the transmission crossmember. The BB engine also was lowered in the front. Unless my memory has crapped out on my, the SB cars had the engine centered in the chassis and was mounted higher. FWIW, you can mount the BB engine on the SB mounts so I don't know why they did it that way.
'61-'67 Chevy II's had the engine offset to the right about an inch. It may have been done get get driver's foot room or it may have been done to get real estate for the V-8 engine. Don't know.
Second generation Chevy II/Nova and first generation Camaros had the BB engines offset to the right at both the engine mounts and the transmission crossmember. The BB engine also was lowered in the front. Unless my memory has crapped out on my, the SB cars had the engine centered in the chassis and was mounted higher. FWIW, you can mount the BB engine on the SB mounts so I don't know why they did it that way.
07-27-2015, 08:42 PM
#18
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The pinion alignment allowed a narrower drive shaft tunnel. Don't try to make something easy, difficult.
'61-'67 Chevy II's had the engine offset to the right about an inch. It may have been done get get driver's foot room or it may have been done to get real estate for the V-8 engine. Don't know.
Second generation Chevy II/Nova and first generation Camaros had the BB engines offset to the right at both the engine mounts and the transmission crossmember. The BB engine also was lowered in the front. Unless my memory has crapped out on my, the SB cars had the engine centered in the chassis and was mounted higher. FWIW, you can mount the BB engine on the SB mounts so I don't know why they did it that way.
'61-'67 Chevy II's had the engine offset to the right about an inch. It may have been done get get driver's foot room or it may have been done to get real estate for the V-8 engine. Don't know.
Second generation Chevy II/Nova and first generation Camaros had the BB engines offset to the right at both the engine mounts and the transmission crossmember. The BB engine also was lowered in the front. Unless my memory has crapped out on my, the SB cars had the engine centered in the chassis and was mounted higher. FWIW, you can mount the BB engine on the SB mounts so I don't know why they did it that way.
http://www.camaros.org/engine.shtml#EngineMounting
07-28-2015, 07:22 AM
#19
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Yeah, the Camaro and '68/later Chevy II/Nova can get pretty confusing on engine mounting without a reference.
Some of the parts houses catalogs have incorrect information in them on part usage.
Some of the parts houses catalogs have incorrect information in them on part usage.
07-28-2015, 12:14 PM
#20
Melting Slicks
If you’re interested, you can buy a copy of Zora’s paper "THE 1963 CHEVROLET - Corvette STING RAY" for $25 (31 pages) from the SAE. There’s also a 5 page preview that can viewed for free.
http://papers.sae.org/630064/
http://papers.sae.org/630064/